Wheat is the most widely cultivated cereal in the world; the grain supplies a major percentage of the nutrients needed by the world’s population. Wheat is one of the oldest domesticated plants—with origins in the Near East at least 9,000 years ago—and it has been argued that it laid the foundation for Western civilization. Wheat grows best in temperate grassland biomes (for more about biomes, see the chapter “Environment and Ecology”) that receive 12 to 36 inches (30 to 90 centimeters) of rain per year and have relatively cool temperatures. Some of the top wheat-producing countries are Argentina, Canada, China, India, the Ukraine, and the United States.